One of the traditional requirements for a military vehicle is the ability to operate under extreme climate conditions that normal vehicle can not tolerate. Military vehicles must often operate under arctic conditions, when, among other things, vehicle batteries have shortened life spans. A particular problem involves the relatively common occurrence wherein a vehicle sits overnight in frigid conditions for 8 to 12 hours after a day of operation. After the 8 to 12 hour period, extra battery power is needed to start the vehicle, yet the battery will have been at a temperature of 30.degree. F. or more below zero for at least several hours. The batteries tend to die or have insufficient power under these conditions. My invention addresses this problem by heating the battery during vehicle operation and keeping the battery warm during overnight vehicle down times or other down times. Consequently, restarting the vehicle is easier and the chance of damaging the battery is reduced.